Well proven plant regulatory compounds are phytohormones. An important place among them has cytokinins. Structurally, all naturally occurring cytokinins belong to the homogenous group of N6-substituted adenine derivatives, playing an important role in many different developmental processes, including cell division, growth and differentiation, as well as flower and fruit development. They can break seed dormancy, inhibit apical dominance and stimulate the growth of side shoots, delay the cell ageing, increase stress resistance, affect cell membrane permeability and cause accumulation of various metabolites in the site of their application (Letham a Palni 1983—Ann. Rev. Plant. Physiol. 34: 163-197, 1983, Mok, D. W. S., Mok, M. C.: Cytokinins: Chemistry, Activity and Function. CRC Press, Boca Raton, London, Tokyo 1994).
Their interaction with auxins is especially important in stimulation of cell division and regulation of cell differentiation in plant tissue cultures (Skoog, Miller 1957). The general definition of cytokinins as group of plant growth regulators is also based on this effect (Skoog, F., Armstrong, D. J.: Cytokinins.—Ann. Rev. Plant Physiol. 21: 359-384, 1970). 6-benzylaminopurin (BAP), together with kinetin, is usually used as an active cytokinin for plant in vitro cultures. This compound was for long time thought to be purely synthetic, however, its natural occurrence in plants was recently proved. There are usually refereed as a cytokinins also a compounds having limited or none biological activity (7- and 9-glucosides, amino acid conjugates, some hyper modified cytokinins in tRNA). From this reason, compounds structurally derived from N6-substituted adenine are refereed as cytokinins also in this application.
Since all living organisms on the Earth have been evolutionary developing together for many millions of years, the presence of regulatory interactions of plant compounds, as cytokinins are, in animals and human can be assumed. Cytokinin-derived compounds probably affect many different molecular mechanisms in animal and human cells. We recently discovered, that novel generations of anti-inflammatory, anticancer, immunosuppressive, antiviral and other drugs could be based on N6-substituted purines and their derivatives.
The aim of this invention to provide anticancer, immunosuppressive, growth-regulatory, morphogenetically active and antisenescence heterocyclic compounds having improved selectivity and efficiency index, i.e. that are less toxic yet more efficacious than analogues known heretofore.